Conventionally, liquid crystal display panels having a liquid crystal layer sandwiched between an upper substrate and a lower substrate are known as display panels used in mobile phones and the like. Among these, liquid crystal display panels using vertical alignment type liquid crystal as the liquid crystal layer (VA mode) are known for having a wide viewing angle. Also, in the vertical alignment type liquid crystal display panel, a method of performing orientation control of liquid crystal is proposed in which a plurality of electrode units smaller than one pixel are provided in each pixel, one pixel being constituted of these electrode units as pixel electrodes.
FIG. 20 shows a pixel structure in a liquid crystal display device disclosed in Patent Document 1, and shows a method of performing orientation control of liquid crystal, for example. FIG. 20(a) is a magnified plan view and FIG. 20(b) is a magnified cross-sectional view. FIG. 20(a) is a plan view showing a pixel structure, and shows the overlap of constituent elements of an element substrate 110 and an opposite substrate 120.
As shown in FIG. 20(a), the liquid crystal device 100 includes a pixel Px constituted of a plurality of pixels D1, D2, and D3 forming one group. The respective pixels D1, D2, and D3 include a pixel electrode 115, and one colored layer of one of the three primary colors (RGB) is provided for each of the three pixels D1, D2, and D3. Therefore, the respective pixels D1, D2, and D3 are respectively a red pixel D1, a green pixel D2, and a blue pixel D3. As shown in FIG. 20(a), in each of the pixels D1, D2, and D3, the pixel electrode 115 is constituted of island-shaped sub-pixel electrodes 115a, 115b, and 115c that are separated from each other. In the sub-pixel electrode 115a, the electrode radiates out from the center, and a plurality of fine cutouts 133 are formed in the periphery of the sub-pixel electrode. Also, in the sub-pixel electrodes 115b and 115c, cutouts 132 that are cut out from a portion of the pixel electrode 115 to separate the pixel electrode 115 into sub-pixel electrodes are formed. By forming the cutouts 132 to separate the pixel electrode 115 into such sub-pixel electrodes, the pixel electrode 115 is formed into separate substantially rectangular sub-pixel electrodes 115b and 115c. In the respective pixels D1, D2, and D3, the respective sub-pixel electrodes 115a, 115b, and 115c are connected to a connecting portion 159 so as to be at the same potential.
As shown in FIG. 20(b), colored layers 122R, 122B, and 122G are provided on an inner side of a main substrate body 120A of the opposite substrate 120 (portion of the main substrate body 120A facing the liquid crystal layer). Also, the peripheries of the respective colored layers are surrounded by a black matrix BM, and the black matrix BM forms the boundaries between the respective pixels D1, D2, and D3 (refer to FIG. 20(a)). On the surface of the colored layers 122R, 122B, and 122G, a common electrode 109 is formed on the entire surface of the opposite substrate 120, and on the inner side of the common electrode 109, protrusions 124 are formed as a way to perform orientation control. These protrusions 124 face substantially the respective centers of the sub-pixel electrodes, and as a result, with the liquid crystal molecules being vertically aligned in an initial state, the inclined surface of the protrusions 124 provides the liquid crystal molecules with a pretilt. As a result, it is possible to control or restrict the direction in which the liquid crystal molecules are inclined, and the liquid crystal molecules are inclined in eight directions from the protrusion 124 when a voltage is applied thereto. In other words, the liquid crystal device 100 has the orientation of the liquid crystal divided among the sub-pixel electrodes 115a, 115b, and 115c in the pixels D1, D2, and D3.
FIG. 21 shows a pixel structure of a liquid crystal display device disclosed in Patent Document 2, and a pixel electrode 220 formed in a pixel area surrounded by gate bus lines 214 and drain bus lines 216 has a plurality of electrode units 240 that have a square outer shaped and that are formed to be smaller than the pixel area, slits 242 of the electrodes formed between adjacent electrode units 240, and connecting electrodes 244 that electrically connect electrode units 240 separated by the slits 242. Each electrode unit 240 has a solid portion 246, and a plurality of trunk portions 248 and branch portions 250 that extend outward in the circumferential direction of the electrode unit 240 from the solid portion 246. Also, as shown in FIG. 21, protruding structures 264 similar to the protrusions 224 shown in FIG. 20(b) are provided in positions facing the solid portions 246 of the respective electrode units 240.